The production cross-sections for W +/- and Z bosons are measured using ATLAS data corresponding to an integrated luminosity of 4.0 pb-1 collected at a centre-ofmass energy v s = 2.76 TeV. The deca ...

Aaboud, M.; Aad, G.; Abbott, B.; Abdinov, O.; Abeloos, B; Abhayasinghe, DK; Abidi, S.H.; Abouzeid, Ossama Sherif Alexander; Abraham, NL; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B.S.; Adachi, Shin-ichi; Adamczyk, L.; Adelman, J.; Adersberger, M.; Adiguzel, A.; Adye, T.; Affolder, A. A.; Afik, Y. ; Besjes, Geert-Jan; Bajic, Milena; Alonso Diaz, Alejandro; de Almeida Dias, Flavia; Dam, Mogens; Hansen, Peter Henrik; Hansen, Jørn Dines; Hansen, Jørgen Beck; Galster, Gorm Aske Gram Krohn; Monk, James William; Petersen, Troels Christian; Thiele, Fabian Alexander Jürgen; Xella, Stefania; Stark, Simon Holm; Wiglesworth, Graig

A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded in 2015 and 2016 by the ATLAS experiment in ffiffiffi s p ¼ TeV proton-proton collisions at the Large Hadron Collider, corresponding to an integrated luminosity of 36 . 1 fb − 1 . The results are interpreted in the context of various models where squarks and gluinos are pair produced and the neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.03 TeV for a simplified model incorporating only a gluino and the lightest neutralino, assuming the lightest neutralino is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.55 TeVare excluded if the lightest neutralino is massless. These limits substantially extend the region of supersymmetric parameter space previously excluded by searches with the ATLAS detector. and the dotted lines are obtained by varying the signal cross section by the renormalization and factorization scale and PDF uncertainties. Results are compared with the observed limits obtained by the previous ATLAS searches with jets, missing transverse momentum, and no leptons [11].

These proceedings present the method and performance of primary vertex reconstruction at the ATLAS experiment during Runs 1 and 2 at the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of , and during 2015-2016 at . Some predictions toward future runs are also presented. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed.

The reconstruction of vertices corresponding to proton-proton collisions in ATLAS is an essential element of event reconstruction used in many performance studies and physics analyses. During Run-1 of the LHC, ATLAS has employed an iterative approach to vertex finding. In order to improve the flexibility of the algorithm and ensure continued performance for very high numbers of simultaneous collisions in Run-2 of the LHC and beyond, a new approach to seeding vertex finding has been developed inspired by image reconstruction techniques. This note provides a brief outline of how reconstructed tracks are used to create an image of likely vertex collisions in an event, describes the implementation in the ATLAS software, and presents some preliminary results of the performance of the algorithm in simulation approximating early Run-2 conditions.